Rabbits and Rodents

By | September 9, 2016

Rodents—which include rats, mice, and squirrels—were as plentiful in prehistoric times as they are today. Rabbits, too, hopped and jumped across the landscape in much the same way as their modern descendants.
Although most were small herbivores, some species grew to a scarily large size.


Key features
■ Rodents have four special incisor teeth that are used for gnawing; rabbits have eight.
■ Furry coats
■ Clawed toes

They first appeared in the Paleogene Period (about 65 million years ago) and still exist today.

Castoroides (CASS-tore-OY-deez)


When: 3 million–10,000 years ago (Neogene)

Fossil location: N. America

Habitat: Lakes, ponds, swamps

Length: 10 ft (3 m)

Diet: Plants

Also known as the giant beaver, Castoroides was about the size of a black bear and was one of the largest rodents ever to have lived. Modern beavers have chisel-like front teeth, but Castoroides’s teeth were broad and large. It had shorter hindlimbs, but its tail was longer and narrower. Like modern beavers, it lived in or near water and perhaps built small dams and domeshaped lodges (beaver homes).


20,000-year-old fossil tooth of a giant beaver.

Palaeocastor (PAY-lee-oh-CASS-tor)


When: 25 million years ago (Paleogene)

Fossil location: USA, Japan

Habitat: Woodlands

Length: 15 in (38 cm)

Diet: Plants

Palaeocastor was a much smaller and earlier beaver than Castoroides. This land-dwelling animal dug deep burrows with its front teeth rather than building dams and lodges. Fossilized burrows with Palaeocastor skeletons and tooth marks on the walls were found in 1891. These famous burrows were called “devil’s corkscrews” because of their narrow, spiral shape.

Eomys (EE-oh-miss)


When: 25 million years ago (Paleogene)

Fossil location: France, Germany, Spain, Turkey

Habitat: Woodlands

Length: 10 in (25 cm)

Diet: Plants

This small rodent could glide through the air. Many Eomys skeletons have been found, showing that it had a long skin membrane between its front and back legs, rather like that of a modern flying squirrel. Eomys is thought to be a close relative of gophers and pocket mice that exist today.

Ceratogaulus (seh-RAT-oh-GAWL-us)


When: 10–5 million years ago (Neogene)

Fossil location: Canada, USA

Habitat: Woodlands

Length: 12 in (30 cm)

Diet: Plants

Known as the horned gopher, Ceratogaulus is the smallest mammal known to have had horns and one of the only horned rodents. Scientists once thought that it used its horns for digging, but their position on the skull makes this unlikely. Both sexes had horns, so they were probably used for defense rather than mating displays. Ceratogaulus lived in burrows that it dug with its large claws. Its eyes were small and its vision was probably poor.


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